Method and apparatus for phonocardiographic image acquisition and presentation

ABSTRACT

A cardiac rhythm management system provides a phonocardiographic image indicative of a heart&#39;s mechanical events related to hemodynamic performance. The phonocardiographic image includes a stack of acoustic sensor signal segments representing multiple cardiac cycles. Each acoustic sensor signal segment includes heart sounds indicative of the heart&#39;s mechanical events and representations of the heart&#39;s electrical events. The stack of acoustic sensor signal segments are aligned by a selected type of the heart&#39;s mechanical or electrical events and are grouped by a cardiac timing parameter for presentation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/307,900, filed Dec. 2, 2002, now U.S. Pat. No. 7,260,429, which ishereby incorporated by reference.

This application is related to commonly assigned Siejko et al. U.S.patent application Ser. No. 10/307,896, entitled “PHONOCARDIOGRAPHICIMAGE-BASED ATRIOVENTRICULAR DELAY OPTIMIZATION,” filed Dec. 2, 2002,now U.S. Pat. No. 7,123,962, which is hereby incorporated by reference.

TECHNICAL FIELD

This document relates generally to cardiac rhythm management systems andparticularly, but not by way of limitation, to such a system providingfor phonocardiographic image-based diagnosis and therapy evaluation.

BACKGROUND

A heart is the center of a person's circulatory system. It includes acomplex electro-mechanical system performing two major pumpingfunctions. The left portions of the heart, including the left atrium andthe left ventricle, draw oxygenated blood from the lungs and pump it tothe organs of the body to provide the organs with their metabolic needsfor oxygen. The right portions of the heart, including the right atriumand the right ventricle, draw deoxygenated blood from the organs andpump it into the lungs where the blood gets oxygenated. These mechanicalpumping functions are accomplished by contractions of the myocardium(heart muscles). In a normal heart, the sinus node, the heart's naturalpacemaker, generates electrical signals, called action potentials, thatpropagate through an electrical conduction system to various regions ofthe heart to excite myocardial tissues in these regions. Coordinateddelays in the propagations of the action potentials in a normalelectrical conduction system cause the various regions of the heart tocontract in synchrony to such that the pumping functions are performedefficiently. Thus, the normal pumping functions of the heart, indicatedby hemodynamic performance, require a normal electrical system togenerate the action potentials and deliver them to designated portionsof the myocardium with proper timing, a normal myocardium capable ofcontracting with sufficient strength, and a normal electro-mechanicalassociation such that all regions of the heart are excitable by theaction potentials.

The function of the electrical system is indicated byelectrocardiography (ECG) with at least two electrodes placed in orabout the heart to sense the action potentials. When the heart functionsirregularly or abnormally, one or more ECG signals indicate thatcontractions at various cardiac regions are chaotic and unsynchronized.Such conditions, which are related to irregular or other abnormalcardiac rhythms, are known as cardiac arrhythmias. Cardiac arrhythmiasresult in a reduced pumping efficiency of the heart, and hence,diminished blood circulation. Examples of such arrhythmias includebradyarrhythmias, that is, hearts that beat too slowly or irregularly,and tachyarrhythmias, that is, hearts that beat too quickly. A patientmay also suffer from weakened contraction strength related todeterioration of the myocardium. This further reduces the pumpingefficiency. For example, a heart failure patient suffers from anabnormal electrical conduction system with excessive conduction delaysand deteriorated heart muscles that result in asynchronous and weakheart contractions, and hence, reduced pumping efficiency, or poorhemodynamic performance.

A cardiac rhythm management system includes a cardiac rhythm managementdevice used to restore the heart's pumping function, or hemodynamicperformance. Cardiac rhythm management devices include, among otherthings, pacemakers, also referred to as pacers. Pacemakers are oftenused to treat patients with bradyarrhythmias. Such pacemakers maycoordinate atrial and ventricular contractions to improve the heart'spumping efficiency. Cardiac rhythm management devices also includedefibrillators that deliver higher energy electrical stimuli to theheart. Such defibrillators may also include cardioverters, whichsynchronize the delivery of such stimuli to portions of sensed intrinsicheart activity signals. Defibrillators are often used to treat patientswith tachyarrhythmias. In addition to pacemakers and defibrillators,cardiac rhythm management devices also include, among other things,devices that combine the functions of pacemakers and defibrillators,drug delivery devices, and any other devices for diagnosing or treatingcardiac arrhythmias. Efficacy of a cardiac rhythm management device ismeasured by its ability to restore the heart's pumping efficiency, orthe hemodynamic performance, which depends on the conditions of theheart's electrical system, the myocardium, and the electro-mechanicalassociation. Therefore, in addition to the ECG indicative of activitiesof the heart's electrical system, there is a need to measure the heart'smechanical activities indicative of the hemodynamic performance,especially with the patient suffers from a deteriorated myocardiumand/or poor electro-mechanical association.

For these and other reasons, there is a need for monitoring bothelectrical and mechanical activities of the heart for diagnostic andtherapy evaluation purposes.

SUMMARY

A cardiac rhythm management system provides a phonocardiographic imageindicative of a heart's mechanical events related to hemodynamicperformance. The phonocardiographic image includes a stack of acousticsensor signal segments representing multiple cardiac cycles. Eachacoustic sensor signal segment includes indications of heart soundsrelated to the heart's mechanical events and representations of theheart's electrical events. The stack of acoustic sensor signal segmentsare aligned by a selected type of the heart's mechanical or electricalevents and are grouped by a cardiac timing parameter for presentation.

In one embodiment, a system includes a signal input, a marker input, asignal segmenting module, and a signal alignment module. The signalinput receives an acoustic sensor signal indicative of heart sounds. Themarker input receives event markers indicative of cardiac events. Theevent markers are temporally associated with the acoustic sensor signal.The signal segmenting module segments the acoustic sensor signal intoacoustic sensor signal segments based on a selected type of the eventmarkers representing a certain type of the cardiac events. The signalalignment module temporally aligns the acoustic sensor signal segmentsbased on the selected type of the event markers. The phonocardiographicimage includes the aligned acoustic sensor signal segments.

In one embodiment, a cardiac rhythm management system includes animplantable device, an acoustic sensor, and an external programmer. Theimplantable device includes a sensing circuit that senses a cardiacsignal indicative of cardiac events and a therapy circuit that deliverstherapies. The acoustic sensor senses an acoustic sensor signalrepresentative of heart sounds. The external programmer communicateswith the implantable device and the acoustic sensor and includes aprocessor, a controller, and a display. The processor receives andanalyzes the cardiac signal and the acoustic sensor signal. An imageformation module of the processor segments the acoustic sensor signalinto acoustic sensor signal segments and temporally aligns the acousticsensor signal segments based on a selected type of the cardiac events.The controller controls the delivery of the therapies. The displaypresents the phonocardiographic image including the aligned acousticsensor signal segments and representations of a selection of the cardiacevents.

In one embodiment, an acoustic sensor signal representative of heartsounds and a cardiac signal indicative of cardiac events are received.The cardiac signal is temporally associated with the acoustic sensorsignal. The acoustic sensor signal is segmented into acoustic sensorsignal segments based on, and aligned by, a selected type of the cardiacevents. The phonocardiographic image including at least the alignedacoustic sensor signal segments and representations of a selection ofthe cardiac events is presented.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsdescribe similar components throughout the several views. Like numeralshaving different letter suffixes represent different instances ofsimilar components. The drawings illustrate generally, by way ofexample, but not by way of limitation, various embodiments discussed inthe present document.

FIG. 1 is a schematic illustration of an embodiment of portions of acardiac rhythm management system and portions of an environment in whichit is used.

FIG. 2 is a conceptual illustration of one embodiment of aphonocardiographic image constructed of an acoustic sensor signal.

FIG. 3 is a schematic/block diagram illustrating one embodiment ofportions of the cardiac rhythm management system with an implantedacoustic sensor.

FIG. 4 is a schematic/block diagram illustrating one embodiment ofportions of the cardiac rhythm management system with an externalacoustic sensor.

FIG. 5 is a schematic/block diagram illustrating one embodiment of asignal processor of the cardiac rhythm management system.

FIG. 6 is a schematic/block diagram illustrating one embodiment of atherapy controller of the cardiac rhythm management system.

FIG. 7 is an illustration of portions of a visual presentation includingan actual phonocardiographic image according to the embodiment of FIG.2.

FIG. 8 is a flow chart illustrating one embodiment of a method foracquiring, presenting, and using the phonocardiographic image.

FIG. 9 is a flow chart illustrating one embodiment of a method forphonocardiographic image-based diagnosis.

FIG. 10 is a flow chart illustrating one embodiment of a method forphonocardiographic image-based therapy evaluation.

FIG. 11 is a flow chart illustrating one specific embodiment of a methodfor phonocardiographic image-based AVD optimization.

FIG. 12 is an illustration of one embodiment of a method for AVDoptimization for maximum ventricular contractility.

FIG. 13 is a flow chart illustrating one embodiment of a method forphonocardiographic image-based AVD optimization for maximum ventricularcontractility.

FIG. 14 is a flow chart illustrating one embodiment of another methodfor phonocardiographic image-based AVD optimization for maximumventricular contractility.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings that form a part hereof, and in which is shown, byway of illustration, specific embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that the embodiments may be combined, or that otherembodiments may be utilized and that structural, logical and electricalchanges may be made without departing from the scope of the presentinvention. The following detailed description is, therefore, not to betaken in a limiting sense, and the scope of the present invention isdefined by the appended claims and their equivalents.

This document discusses, among other things, a phonocardiographic imageindicative of a heart's mechanical events related to the heart's pumpingfunctions and hemodynamic performance to allow, among other things,diagnosis of cardiac conditions and evaluation of therapies treating thecardiac conditions. The present method and apparatus will be describedin applications involving implantable cardiac rhythm management systemssuch as systems including pacemakers, cardioverter/defibrillators,pacer/defibrillators, and cardiac resynchronization therapy (CRT)devices. However, it is to be understood that the present methods andapparatuses may be employed in other types of medical devices,including, but not being limited to, external cardiac rhythm managementsystems, drug delivery systems, and various types of cardiac monitoringdevices.

FIG. 1 is a schematic illustration of an embodiment of portions of acardiac rhythm management system 100 and portions of an environment inwhich it is used. In one embodiment, system 100 is a cardiac rhythmmanagement system including, among other things, an implanted device 110and an external programmer 140. Implanted device 110 is implanted withina patient's body 101 and coupled to the patient's heart 102 by a leadsystem 105. Examples of implanted device 110 include pacemakers,cardioverter/defibrillators, pacemaker/defibrillators, CRT devices, anddrug delivery devices. Programmer 140 includes a user interface forsystem 100. Throughout this document, the “user” refers to a physicianor other caregiver who examines and/or treats the patient with system100. The user interface allows a user to interact with implanted device110 through a telemetry link 170.

In one embodiment, as illustrated in FIG. 1, telemetry link 170 is aninductive telemetry link supported by a mutual inductance between twoclosely-placed coils, one housed in a wand 175 near or attached ontobody 101 and the other housed in implanted device 110. In an alternativeembodiment, telemetry link 170 is a far-field telemetry link. In oneembodiment, telemetry link 170 provides for data transmission fromimplanted device 110 to programmer 140. This may include, for example,transmitting real-time physiological data acquired by implanted device110, extracting physiological data acquired by and stored in implanteddevice 110, extracting therapy history data stored in implanted device110, and extracting data indicating an operational status of implanteddevice 110 (e.g., battery status and lead impedance). In a furtherembodiment, telemetry link 170 provides for data transmission fromprogrammer 140 to implanted device 110. This may include, for example,programming implanted device 110 to acquire physiological data,programming implanted device 110 to perform at least one self-diagnostictest (such as for a device operational status), and programmingimplanted device 110 to deliver at least one therapy.

In one embodiment, programming implanted device 110 includes sendingtherapy parameters to implantable device 110. In one embodiment, thetherapy parameters provide an approximately optimal hemodynamicperformance to a patient by delivering cardiac pacing pulses to thepatient's heart. To determine approximately optimal therapy parameters,i.e., therapy parameters providing for the approximately optimalhemodynamic performance, there is a need to diagnose the heart'sconditions and/or evaluate the hemodynamic performance with differenttherapy types and/or parameters. The need is met by using aphonocardiographic image simultaneously showing electrical events,mechanical events and electro-mechanical time intervals for multiplecardiac cycles. The electrical events include, by way of example, butnot by way of limitation, intrinsic depolarizations and deliveries ofpacing pulses. The mechanical events and electromechanical timeintervals include, by way of example, but not by way of limitation,mitral valve closure, aortic valve opening and closure,electromechanical activation delays, isovolumic contraction time,ejection period, and diastolic filling period.

In one embodiment, the phonocardiographic image is formed based on asignal acquired by using an acoustic sensor placed in or about heart 102to directly or indirectly sense heart sounds indicative of mechanicalactivities of heart 102. In one embodiment, the acoustic sensor is amicrophone. In another embodiment, the acoustic sensor is anaccelerometer. In one embodiment, as shown in FIG. 1, the acousticsensor is an external sensor 130 attached on to body 101 near heart 102.External sensor 130 is connected to programmer 140 via a cable throughwhich an acoustic sensor signal representing heart sounds is transmittedto programmer 140. In another embodiment, the acoustic sensor is animplanted acoustic sensor that is housed in implanted device 110 orotherwise connected to implanted device 110. An acoustic sensor signalrepresenting heart sounds is transmitted to programmer 140 via telemetrylink 175.

FIG. 2 is a conceptual illustration of one embodiment of thephonocardiographic image. The phonocardiographic image simultaneouslypresents multiple cardiac cycles each including representations orindications of electrical and mechanical events of heart 102 that occurduring the cycle. In one embodiment, the electrical events includeintrinsic depolarizations sensed from, and pacing pulses delivered to,heart 102. These electrical events are referred to as cardiac events. Inone embodiment, the mechanical events of heart 102 are indicated byheart sounds. In one embodiment, as illustrated in FIG. 2, thephonocardiographic image includes a horizontal axis indicating time anda vertical axis indicating cardiac cycles. The cardiac events and heartsounds during each cardiac cycle is presented at the same verticallevel. In one embodiment, the phonocardiographic image includes a stackof signal segments each represent at least one cardiac cycle includingcardiac events and heart sounds detected during that cardiac cycle. Inanother embodiment, the phonocardiographic image includes stacked signalsegments each represent at least a portion of a cardiac cycle includingselected cardiac events and heart sounds detected during that cardiaccycle. In one embodiment, as illustrated in FIG. 2 by way of example,but not by way of limitation, the phonocardiographic image includes astack of signal segments each include one complete cardiac cycle betweentwo cardiac events A, and includes representations or indications ofdetected cardiac events A and V and heart sounds S1, S2, and S3. Cardiacevent A represents an atrial event that is either an intrinsicdepolarization sensed from an atrium or a pacing pulse delivery to theatrium. Cardiac event V represents a ventricular event that is either anintrinsic depolarization sensed from a ventricle or a pacing pulsedelivery to the ventricle. Heart sound S1 represents the “first heartsound,” which is known to be indicative of, among other things, mitralvalve closure, tricuspid valve closure, and aortic valve opening. Heartsound S2 represents the “second heart sound,” which is known to beindicative of, among other things, aortic valve closure and pulmonaryvalve closure. Heart sound S3 represents the “third heart sound,” whichis known to be indicative of certain pathological conditions includingheart failure. In other embodiments, the phonocardiographic imageinclude representations and/or indications of one or more of othercardiac events and heart sounds such as the “fourth heart sound” andvarious components of the first, second, and third heart sounds.

In one embodiment, the phonocardiographic image includes the stack ofsignal segments aligned by a selected cardiac event or heart sound thatpresents during each cardiac cycle. This facilitates observation oftrends of times of heart sounds and/or time intervals between any two ofthe cardiac events and heart sounds over multiple cardiac cycles. In oneembodiment, as illustrated in FIG. 2, the signal segments are aligned bycardiac event A. This allows, for example, observation of a trend of theA-S1 interval, indicative of an electro-mechanical interval betweenatrial contraction and mitral valve closure (A-MC interval), overmultiple cardiac cycles. In another embodiment, the signal segments arealigned by cardiac event V. Generally, any repetitious cardiac event orheart sound can be used for the alignment of the signal segments,depending on the specific need to facilitate observation of, ordetection from, the phonocardiograph image. In one embodiment, asillustrated in FIG. 2, the A-S1 interval trend indicates the effect of ashortened A-V time interval on the timing of mitral valve closure. Inone embodiment, the shortened A-V time interval is a result of cardiacpacing using an atrio-ventricular delay (AVD) that is shorter than anintrinsic atrio-ventricular interval (AVI). In other embodiments, thesignal segments may be aligned by any of the cardiac events and heartsounds represented or indicated in the phonocardiograph image, such asany of A, V, S1, S2, and S3, for example, depending on the specifictrend to be observed.

In one embodiment, the phonocardiographic image includes the stack ofsignal segments arranged in a selected order. This further facilitatesthe observation of the timing trends. In one embodiment, the signalsegments are arranged by the values of a specific timing interval orparameter associated with each of the signal segments to facilitateobservation of the timing trends over the specific timing interval orparameter. In one embodiment, as illustrated in FIG. 2, the signalsegments are arranged by the values of the A-V time interval. Thisfacilitates observation of the A-S1 interval trend over the A-V timeinterval. When the A-V time interval varies as a result of cardiacpacing at various AVDs, the phonocardiographic image facilitatesobservation of the trend of the A-S1 interval over AVDs of the cardiacpacing. In a further embodiment, selected signal segments such as thesignal segments associated with the same A-V time interval are averaged.When the A-V time interval varies as a result of cardiac pacing atvarious AVDs, the phonocardiographic image facilitates observation ofthe trend of the averaged A-S1 interval over AVDs of the cardiac pacing.In another further embodiment, one of the AVDs is selected based on adesirable A-S1 interval indicative of an approximately optimalelectro-mechanical interval between atrial contraction and mitral valveclosure. In another related embodiment, as illustrated in FIG. 2, heartsound S3 is observed to be present only during the cardiac cycles orsignal segments associated with relatively long A-V time intervals. Thisindicates that pacing improves cardiac conditions of a heart failurepatient by shortening the A-V time interval. In other embodiments, thesignal segments may be arranged by any of the intrinsic and therapy timeintervals observable from the phonocardiographic image, depending on thetrend to be observed. For example, if the trend of an electro-mechanicalinterval over heart rate and/or pacing rate is of interest, the signalsegments may be arranged by the atrial cycle length interval (timeinterval between two consecutive cardiac events A) or the ventricularcycle length interval (time interval between two consecutive cardiacevents V).

FIG. 3 is a schematic/block diagram illustrating one embodiment ofportions of cardiac rhythm management system 100 with an implantedacoustic sensor 335. System 100 provides for acquisition of at least acardiac signal and an acoustic sensor signal indicating the cardiacevents and heart sounds represented or indicated in thephonocardiographic image. In one embodiment, system 100 includes animplanted portion and an external portion. The implanted portion resideswithin body 101 and includes implanted device 110 and lead system 105providing for electrical connection between implanted device 110 andheart 102. The external portion includes programmer 140 and wand 175connected to programmer 140. Telemetry link 170 provides forbi-directional communications between implanted device 110 andprogrammer 140.

In one embodiment, lead system 105 includes one or more leads havingendocardial electrodes for sensing cardiac signals referred to asintracardiac ECGs, or electrograms. In one embodiment, lead system 105includes at least an atrial lead and a ventricular lead. In oneembodiment, as illustrated in FIG. 3, lead system 105 includes an atriallead 105A having at least one electrode placed within the right atrium,a right ventricular lead 105B having at least one electrode placedwithin the right ventricle, and a left ventricular lead 105C having atleast one electrode placed in or about the left ventricle. In onespecific embodiment, lead 105C includes at least one electrode placed incoronary venous vasculature traversing the left ventricle. Such leadsystem allows for CRT including left ventricular, right ventricular, orbiventricular pacing.

In one embodiment, implanted device 110 includes a sensing circuit 321,a therapy circuit 322, an implant controller 323, an implant telemetrymodule 324, a coil 325, an implanted acoustic sensor 335, an implantedsensor circuit 336, and a power source 320. Sensing circuit 321 includesone or more sensing amplifiers each sense a cardiac signal from acardiac location where an endocardial electrode of lead system 105 isplaced. Therapy circuit 322 includes one or more therapy output circuitsthat deliver one or more therapies to heart 102. In one embodiment,therapy circuit 322 includes one or more pacing output circuits eachdeliver pacing pulses to a cardiac location where an endocardialelectrode of lead system 105 is placed. In another embodiment, therapycircuit 322 includes one or more defibrillation output circuits eachdeliver defibrillation shocks to a cardiac location. In a furtherembodiment, therapy circuit 322 includes one or more pacing outputcircuit and one or more defibrillation output circuits. Implantedacoustic sensor 335 senses an acoustic signal including heart soundsindicative of mechanical events of heart 102 and converts the acousticsignal to an acoustic sensor signal representing the acoustic signal. Inone embodiment, the acoustic sensor signal has a voltage amplitudeassociated with the intensity of the acoustic signal. In one embodiment,implanted acoustic sensor 335 includes a microphone. In anotherembodiment, implanted acoustic sensor 335 includes an accelerometer. Inone embodiment, the accelerometer is also used to sense movements ofimplanted device 110 or body 101 to monitor a metabolic need of theorgans of body 101. Implant controller 323 controls the operation ofimplanted device 110. In one embodiment, implant controller 323 includesa memory circuit on which therapy instructions and parameters arestored. The controller executes the therapy instructions to deliver oneor more therapies to heart 102 with the therapy parameters. In oneembodiment, the therapy instructions are programmed into the memorycircuit when implant device 110 is built, and the therapy parameters areprogrammed into the memory circuit by programmer 140 via telemetry link170. In another embodiment, both the therapy instructions and parametersare programmed to the memory circuit by programmer 140 via telemetrylink 170. In one embodiment, the therapy parameters stored in the memorycircuit are dynamically updated by programmer 140 via telemetry link 170during or between therapy deliveries. In one embodiment, the therapyinstructions includes a therapy algorithm that controls each therapydelivery based on one or more cardiac signals sensed through lead system105 and sensing circuit 321, the acoustic sensor signal acquired throughimplanted acoustic sensor 335 and implanted sensor circuit 336, and thetherapy parameters. In one embodiment, the therapy includes a pacingtherapy; the therapy instructions includes at least one pacing algorithmthat controls delivery of pacing pulses on a beat-by-beat basis based onthe one or more cardiac signals, the acoustic sensor signal, and pacingparameters stored in the memory circuit. In one specific embodiment, thetherapy instructions stored in the memory circuit include therapyinstructions for pacing modes of at least a VDD type and a DDD type. Thetherapy parameters stored in the memory circuit include pacingparameters including at least one AVD. In this embodiment, implantcontroller 323 times each delivery of a pacing pulse to the heart. Inone embodiment, implant controller 323 processes the one or more cardiacsignals and acoustic sensor signals to control the therapy deliveriesand to transmit the signals or their representations to programmer 140through telemetry link 170. In one embodiment, implant controller 323detects cardiac events from the cardiac signals and marks each detectedcardiac events with event markers each indicative of a type and anapproximate time of occurrence or detection of a detected cardiac event.In this embodiment, therapy deliveries are also marked with other eventmarkers each indicative of a type and an approximate time of delivery ofa therapy. In one specific embodiment, each delivery of the therapy is adelivery of a pacing pulse. In one embodiment, event markersrepresenting detected cardiac events and therapy deliveries aretransmitted to programmer 140 via telemetry link 170. Implant telemetrymodule 324 and coil 325 constitute portions of implanted device 110 thatsupport telemetry link 170.

In one embodiment, controller 323 controls the transmission of signalsacquired by implanted device 110 to programmer 140 via telemetry link170. The signals include the cardiac signal and/or the acoustic sensorsignal. In one embodiment, controller 323 digitizes the signals suchthat cardiac signal samples and/or acoustic sensor signal samples aretransmitted to programmer 140 via telemetry link 170.

In one embodiment, all the components of implanted device 110, includingsensing circuit 321, therapy circuit 322, implant controller 323,implant telemetry module 324, coil 325, implanted acoustic sensor 335,implanted sensor circuit 336, and a power source 320, are housed in ahermetically sealed metal can. In another embodiment, implanted acousticsensor 335 is external to the can but is electrically connected toimplanted sensor circuit 336 housed within the can. In a furtherembodiment, implanted acoustic sensor 335 is attached to a lead of leadsystem 105 and placed in heart 102. It is electrically connected toimplanted sensor circuit 336 housed within the can through the lead. Inone specific embodiment, the lead has a proximal end connected tosensing circuit 321 and a distal end disposed in the heart. Implantedacoustic sensor 335 is attached to the lead at or near its distal end.

Power source 320 supplies all energy needs of implanted device 110. Inone embodiment, power source 320 includes a battery or a battery pack.In a further embodiment, power source 320 includes a power managementcircuit to minimize energy use by implant device 110 to maximize itslife expectancy.

In one embodiment, programmer 140 includes a signal processor 350, atherapy controller 360, a display 341, a user input module 342, and aprogrammer telemetry module 345. Programmer telemetry module 345 andwand 175, which is electrically connected to programmer telemetry module345, constitute portions of programmer 140 that support telemetry link170. In one embodiment, signal processor 350 receives signalstransmitted from implanted device 110 via telemetry link 170 andprocesses the signals for presentation on display 341 and/or use bytherapy controller 360. The received signals may include the one or morecardiac signals, representations of cardiac events such as the eventmarkers, and the acoustic sensor signal. In one embodiment, signalprocessor 350 includes an image formation module that forms aphonocardiographic image based on the concepts discussed above withreference to FIG. 2. Details about the image formation module arediscussed below, with reference to FIG. 5. In one embodiment, therapycontroller 360 generates therapy parameters to be transmitted toimplanted device 110 via telemetry link 170. In one embodiment, therapycontroller 360 receives user-programmable parameters from user inputmodule 342 and converts them into code recognizable by implanted device110. In another embodiment, therapy controller 360 includes an automatictherapy protocol execution module that generates therapy parametersbased on a therapy protocol defining a sequences of therapies each beingapplied for a certain time period or number of heart beats. This allowsfor identifying a therapy producing desirable result such as theapproximately optimal hemodynamic performance. Details about the therapyprotocol and the automatic therapy protocol execution module arediscussed below with reference to FIG. 6. Signals acquired by implanteddevice 110 and processed by signal processor 350, including thephonocardiographic image, are presented on display 341. In oneembodiment, where the acoustic sensor signal is digitized, signalprocessor 350 converts acoustic sensor signal samples to image pixelsfor presentation on display 341. In one embodiment, user input module342 receives commands from the user to control or adjust the format ofthe presentation of the phonocardiographic image. In one embodiment,display 341 is an interactive display that includes at least portions ofuser input module 342, such that the user may enter commands bycontacting display 341. In one embodiment, user input module 342includes a zooming module to allow the user to enlarge a selectedportion of the phonocardiographic image. In one embodiment, user inputmodule 342 includes an electronic caliper module to allow the user tomeasure a time interval between any two points along any of the acousticsensor signal segments. In one embodiment, user input module 342comprises a video control module to allow the user to adjust at leastone of a brightness, contrast, and color related to presenting thephonocardiographic image.

In one embodiment, programmer 140 is a computer-based device. In onespecific embodiment, programmer 140 is built on a notebook computer.Signal processor 350 and therapy controller 360 are each implemented asone of a hardware, a firmware, a software, or a combination of any ofthese. In one embodiment, signal processor 350 and therapy controller360 each include software that need to be installed on programmer 140only if a phonocardiographic image based diagnosis or aphonocardiographic image based therapy parameter evaluation is intendedto be performed with that programmer. In one embodiment, programmer 140performs a variety of functions, including the phonocardiographicimage-related functions as optional functions. The software supportingthe phonocardiographic image-related functions are stored on one or morestorage media for installation when needed.

FIG. 4 is a schematic/block diagram illustrating one embodiment ofportions of the cardiac rhythm management system 100 with an externalacoustic sensor. System 100 in this embodiment differs from system 100in the embodiment of FIG. 3 in that the acoustic sensor is externallyplaced onto body 101. In this embodiment, system 100 includes externalacoustic sensor 130 that is attached onto body 101. The location on body101 where external acoustic sensor 130 is placed onto depends on themechanical events of interest. For example, when external acousticsensor 130 is used to detect the first heart sound indicative of mitralvalve closure, the sensor is attached onto body 101 over heart 102 nearits mitral valve. External acoustic sensor 130 is connected to anexternal sensor circuit 431, which processes the acoustic sensor signalfor being received by signal processor 350. In one embodiment, externalsensor circuit 431 digitizes the acoustic sensor signal to produce theacoustic sensor signal samples that are converted to image pixels forpresentation on display 341. In another embodiment, signal processor 350digitizes the acoustic sensor signal. In one embodiment, as illustratedin FIG. 4, external sensor circuit 431 is part of programmer 140. In analternative embodiment, external sensor circuit 431 is connected toprogrammer 140 and functions as an interface between external acousticsensor 130 and programmer 140.

In addition to the embodiments discussed with reference to FIG. 3 andFIG. 4, the phonocardiographic image can be formed with a cardiac signaland an acoustic sensor signal acquired by any implanted or externalsystem providing for ECG and heart sound monitoring. In one embodiment,a surface electrode system including two or more surface ECG electrodesare attached to the skin of the patient to sense a surface ECG as thecardiac signal used to form the phonocardiographic image.

FIG. 5 is a schematic/block diagram illustrating one embodiment ofsignal processor 350. Among other functions, signal processor 350produces the phonocardiographic image. In one embodiment, signalprocessor 350 includes, among other functional components, an acousticsensor signal input 557, a cardiac signal input 558, and an imageformation module 551. In one embodiment, acoustic sensor signal input557 receives the acoustic sensor signal sensed by implanted acousticsensor 335 and transmitted to programmer 140 via telemetry link 170. Inan alternative embodiment, acoustic sensor signal input 557 receives theacoustic sensor signal sensed by external acoustic sensor 130 andtransmitted to programmer 140 via wired electrical connections. In oneembodiment, cardiac signal input 558 receives the one or more cardiacsignals sensed by sensing circuit 321 and transmitted to programmer 140via telemetry link 170. The cardiac signals each include indications ofintrinsic depolarizations and therapy deliveries. In another embodiment,cardiac signal input 558 receives the event markers representative ofthe intrinsic depolarizations and therapy deliveries.

In one embodiment, image formation module 551 includes a signalsegmenting module 552, a signal alignment module 553, a signal groupingmodule 554, a heart sound detector 555, and a video presentation module556. In one embodiment, signal segmenting module 552 partitions theacoustic sensor signal into segments each including at least onecomplete cardiac cycle. In another embodiment, signal segmenting module552 partitions the acoustic sensor signal into segments each includingat least a portion of each cardiac cycle that includes all the requiredor desirable representations or indications of the cardiac events andheart sounds within that cardiac cycle. In a further embodiment, signalsegmenting module 552 partitions the acoustic sensor signal based on aselected type of cardiac events or heart sounds. This facilitatesobservation of timing trends of cardiac events and heart sounds relativeto the selected type of cardiac events. Signal alignment module 553aligns all the acoustic sensor signal segments by the selected type ofcardiac events or heart sounds. This facilitates observation of timingtrends related to the heart sounds, especially time intervals between aselected type of the heart sounds and the selected type of cardiacevents. Signal grouping module 554 sorts and groups the acoustic sensorsignal segments according to a grouping instruction such that thephonocardiographic image presents the acoustic sensor signal segments ina predetermined order or arrangement. In one embodiment, signal groupingmodule 554 sorts and groups the acoustic sensor signal segments based onone or more of therapy parameters and cardiac parameters as provided bythe grouping instruction, such as pacing rate, AVD, heart rate, andcardiac cycle length intervals (atrial cycle length interval andventricular cycle length interval). This allows observation and analysisof heart sounds in relation with such one or more therapy parameters orcardiac parameters. In a further embodiment, signal grouping module 554includes a signal segment averaging module that averages acoustic sensorsignal segments selected according to the grouping instruction. In onespecific embodiment, the signal segment averaging module averages theacoustic sensor signal segments associated with a common therapy orcardiac parameter value or range of values. In one embodiment, thegrouping instruction, including the predetermined order or arrangementand/or the acoustic sensor signal segment averaging, is entered by theuser through user input module 342. Heart sound detector 555 detects aselected type of heart sounds and presents representations of thedetected heart sounds in the phonocardiographic image to furtherfacilitate the observation of timing trends. In one embodiment, heartsound detector 555 detects a beginning, or a leading edge, of each ofthe selected type of heart sounds. In one embodiment, heart sounddetector 555 detects heart sounds by using filtering techniques that arediscussed in Carlson et al., U.S. Pat. No. 5,674,256, entitled “CARDIACPRE-EJECTION PERIOD DETECTION,” assigned to Cardiac Pacemakers, Inc.,the disclosure of which is incorporated herein by reference in itsentirety. In one embodiment, video presentation module 556 converts theacoustic sensor signal samples to image pixels for presentation ondisplay 341. Information included in the acoustic sensor signal, such asintensity of heart sounds, is coded in the image pixels. In oneembodiment, each image pixel represents a single acoustic sensor signalsample. In another embodiment, each image pixel represents a valuecalculated from a predetermined number of acoustic sensor signal samplesusing a predetermined mathematical formula. In one specific embodiment,video presentation module 556 averages several acoustic sensor signalsamples to present an acoustic sensor signal segment indicative of heartsounds with an intensity averaged over a predetermined number of cardiaccycles. In one embodiment, video presentation module 556 includes animage enhancer. In one specific embodiment, video presentation module556 filters the acoustic signal segments to enhance thephonocardiographic image by increasing the contrast.

In one embodiment, at least portions of signal processor 350, includingacoustic sensor signal input 557, cardiac signal input 558, and imageformation module 551, are implemented as software. In one embodiment,this software is a stand-alone software, or a portion thereof, that isstored on a compute-readable storage medium. In one embodiment, thissoftware is installed in a computer for an off-line analysis based onrecorded cardiac signal and acoustic sensor signal.

FIG. 6 is a schematic/block diagram illustrating one embodiment oftherapy controller 360. Therapy controller 360 allows the user to, forexample, select a therapy, start the therapy, stop the therapy, andadjust parameters associated with the therapy. In one embodiment,therapy controller 360 converts user commands and selections received byuser input module 342 to codes recognizable by implanted device 110, andsends the codes to implanted device 110 through telemetry link 170. Inone embodiment, therapy controller 360 includes, among other functionalcomponents, a therapy protocol synthesizer 661 and an automatic therapyprotocol execution module 667. In one embodiment, a therapy protocolincludes therapy descriptions including a sequence of therapy parametersets defining a sequence of therapies to be evaluated with a patient. Inone embodiment, the therapy protocol defines a time period or a numberof heart beats over which each of the therapies is to be delivered. Inone embodiment, the therapy protocol includes therapy descriptionsdefining a sequence of therapies of the same type but each including atleast one parameter whose value differs from that of the othertherapies. In one embodiment, the therapy protocol includes therapydescriptions defining a sequence of alternating therapies andnon-therapies. In other words, a “resting” or “washing” period isprovided between therapy deliveries, such that the effects of eachtherapy can be isolated for analysis. The purpose for executing such atherapy protocol includes identifying a therapy type and/or a therapyparameter or parameter set associated with a desirable therapeuticresult. In one embodiment, the therapeutic result is observed from thephonographic image discussed above with reference to FIG. 2.

In one embodiment, therapy protocol synthesizer 661 includes a cardiacparameter input 662, a therapy parameter calculator 663, and a therapyprotocol generator 664. Cardiac parameter input 662 receives at leastone cardiac parameter related to the patient. In one embodiment, thecardiac parameter is entered by the user. In another embodiment, thecardiac parameter is measured by signal processor 350 from the cardiacsignals and/or event markers telemetered from implanted device 110.Therapy parameter calculator 663 calculates a series of therapyparameters based on the cardiac parameter. Therapy protocol generator664 generates the therapy descriptions defining a sequence of therapieseach including a parameter set defining a therapy using the calculatedtherapy parameters.

In one embodiment, automatic therapy protocol execution module 667includes a therapy parameter sequencing module 669 and a timer 668.Therapy parameter sequencing module 669 sends the therapy descriptionsdefining a sequence of therapies to implanted device 110 via telemetrylink 170, one portion (description of one of the sequence of therapies)at a time, as timed by timer 668. In one embodiment, therapy parametersequencing module 669 sends a description containing a completeparameter set defining a therapy before or at the beginning of aprotocol execution, and then sends further therapy descriptionscontaining only therapy parameters whose values change during theprotocol execution. In one embodiment, timer 668 starts timing apredetermined time period when therapy parameter sequencing module 669sends a therapy description. It signals therapy parameter sequencingmodule 669 to send the next therapy description after the time periodhas elapsed. In another embodiment, timer 668 includes a heart beatcounter that starts beat counting when therapy parameter sequencingmodule 669 sends a therapy description. It signals therapy parametersequencing module 669 to send the nest therapy description after apredetermined number if beats have been counted.

In one embodiment, the therapy protocol is a pacing protocol designed toevaluate pacing parameters by observing hemodynamic performance of thepatient in response to pacing therapies using these pacing parameters.In one embodiment, the pacing protocol includes descriptions of asequence of pacing patterns each including a distinctive AVD. Thepurpose for executing such a pacing protocol includes identification ofan approximately optimal AVD, which is associated with the approximatelyoptimal hemodynamic performance. In one embodiment, the pacing protocolincludes AVDs calculated from a patient's intrinsic AVI or anothermeasured physiological time interval. The pacing protocol includes asequence of alternating pacing and non-pacing periods, with thecalculated AVDs included in the pacing periods in a randomized order. Ina further embodiment, the sequence is repeated for a number of times,with the order of the calculated AVDs randomized separately for eachrepetition. The purpose for alternating the pacing and non-pacingperiods and repeating the sequence with individually randomized order ofAVDs includes isolating the effect of pacing at each AVD during astatistical analysis of the results obtained by executing the pacingprotocol with a patient.

FIG. 7 is an illustration of portions of a visual presentation includingan actual phonocardiographic image 780 according to the embodiment ofFIG. 2. In one embodiment, the visual presentation is displayed ondisplay 341. Phonocardiographic image 780 is shown in FIG. 7, by way ofexample, but not by way of limitation, an implementation of the conceptsdiscussed above with reference to FIG. 2. It is formed based on cardiacevents and an accelerometer signal recorded during a pacing protocolexecution. The pacing protocol is designed to test the effect of atrialtracking mode pacing (VDD mode pacing with multiple ventricular sites)with five different AVDs, AVD1-AVD5, on the hemodynamic performance of apatient suffering congestive heart failure but having a normal sinusnode. The pacing protocol includes a sequence of alternating pacing andnon-pacing periods, with AVD1-AVD5 calculated based on an intrinsic AVImeasured from the patient and included in the pacing periods in arandomized order. The sequence is repeated for a predetermined number oftimes for statistical significance of the results, with the order ofAVD1-AVD5 randomized separately for each repetition.

In accordance with the concepts discussed above with reference to FIG.2, phonocardiographic image 780 includes stacked accelerometer signalsegments aligned by atrial sense markers (Asense) and arranged by theAVDs and AVI. Event markers temporally associated with eachaccelerometer signal segment are superimposed onto the accelerometersignal segment. Accelerometer signal segments associated with the AVIare resulted from the non-pacing periods, and accelerometer signalsegments associated with the AVD1-AVD5 are resulted from periods ofpacing at each of the AVDs. Ventricular event markers (V) presentintrinsic ventricular depolarizations (when appearing on anaccelerometer signal segment associated with the AVI) and deliveries ofventricular pacing pulses (when appearing on an accelerometer signalsegment associated with one of the AVD1-AVD5).

In one embodiment, as illustrated in FIG. 7, amplitude of the acousticsensor signal, indicative of presence and intensity of the heart sounds,is coded in the image pixels for presentation on display 341. In onespecific embodiment, the amplitude of the acoustic sensor signal iscoded in the image pixels such that the amplitude is indicated ondisplay 341 by gray scales. Phonocardiographic image 780 shows the firstheart sound S1, the second heart sound S2, and the third heart sound S3as relatively darker portions of each accelerometer signal segment. In afurther embodiment, the amplitude levels correspond to gray scales withuser-adjustable mapping. User input module 342 includes a mapping moduleto map an intensity of the acoustic sensor signal to the gray scalesaccording to user commands. In another embodiment, the amplitude of theacoustic sensor signal is coded in the pixels such that the amplitude isindicated in display 341 by colors. In a further embodiment, theamplitude levels correspond to a spectrum of colors with user-adjustablemapping. User input module 342 includes a mapping module to map anintensity of the acoustic sensor signal to the spectrum of colorsaccording to user commands.

In one embodiment, display 341 is an interactive display coupled to userinput module 342 such that the user may enter commands or select optionsthrough display 341. In one embodiment, the user may select one of theacoustic sensor signal segments (e.g., acoustic sensor signal segment791) by pointing a cursor to it, and causes display 341 to furtherdisplay a planar acoustic sensor signal-verses-time curve that is thepresentation of the selected acoustic sensor signal segment presented ina different form (e.g., acoustic sensor signal-verses-time curve 790).

FIG. 8 is a flow chart illustrating one embodiment of a method foracquiring, presenting, and using the phonocardiographic image. At 800, aphonocardiograph session is started. In one embodiment, the user startsthe phonocardiograph session by entering a command to programmer 140through user input module 342. At 810, acoustic sensor signal input 557receives an acoustic sensor signal indicative of mechanical events ofheart 102. In one embodiment, the acoustic sensor signal is anaccelerometer signal indicative of heart sounds. In an alternativeembodiment, the acoustic sensor signal is a microphone signal indicativeof heart sounds. At 812, cardiac signal input 558 receives a cardiacsignal. In one embodiment, the cardiac signal is an intracardiacelectrogram indicative of intrinsic cardiac depolarizations and therapydeliveries. In an alternative embodiment, the cardiac signal is asurface ECG. In another alternative embodiment, the cardiac signalincludes event markers representative of intrinsic cardiacdepolarizations and therapy deliveries. At 814, user input module 342receives user instruction defining a presentation of thephonocardiographic image. The user instruction includes one or moretypes of the cardiac events or heart sounds used for segmenting andaligning the acoustic sensor signal segments, arrangement of theacoustic sensor signal segments for presentation, and other presentationformat instructions. At 820, signal processor 350 associates theacoustic sensor signal and the cardiac signal by aligning the twosignals to a common timing reference. In one embodiment, the acousticsensor signal and the cardiac signal are received simultaneously. Thatis, steps 810 and 812 are performed simultaneously. Signal processor 350aligns the acoustic sensor signal and the cardiac signal by aligningpoints or portions of the two signals that are recorded at the sametime. At 830, signal segmenting module 552 partitions the receivedacoustic sensor signal into acoustic sensor signal segments. In oneembodiment, the acoustic sensor signal segments each represent at leastone cardiac cycle including representations or indications of thecardiac events and heart sounds detected during that cardiac cycle. Inanother embodiment, the acoustic sensor signal segments each representat least a portion of a cardiac cycle including selected representationsor indications of the cardiac events and heart sounds detected duringthat cardiac cycle. In one embodiment, points of segmenting aredetermined based on the user instruction received at 814. In thisembodiment, signal segmenting module 552 partitions the acoustic sensorsignal based on the one or more types of the cardiac events and heartsounds. In one embodiment, points of segmenting are related to timesassociated with the event markers. At 840, signal alignment module 553aligns all the acoustic sensor signal segments by the selected type ofcardiac events or heart sounds. In one embodiment, this alignmentfacilitates observation of timing trends related to the heart sounds,especially time intervals between a selected type of the heart soundsand the selected type of cardiac events. In one embodiment, the selectedtype of cardiac events includes atrial contraction. In anotherembodiment, the selected type of cardiac events includes ventricularcontraction. In one embodiment, signal alignment module 553 aligns allthe acoustic sensor signal segments by pre-selected type of cardiacevents or heart sounds. In another embodiment, signal alignment module553 aligns all the acoustic sensor signal segments according to the userinstruction received at 814. At 850, signal grouping module 554 sortsand groups the acoustic sensor signal segments. In one embodiment,signal grouping module 554 sorts and groups the acoustic sensor signalsegments to present them in a pre-defined or default order. In anotherembodiment, signal grouping module 554 sorts and groups the acousticsensor signal segments to arrange them according to the user instructionreceived at 814. In one embodiment, signal grouping module 554 sorts andgroups the acoustic sensor signal segments to present them in an orderrelated to values of a therapy parameter or a measured cardiac parametersuch as AVD, pacing rate, heart rate, and cardiac cycle length intervalmeasured at an atrium or ventricle. In a further embodiment, signalgrouping module 554 averages the acoustic sensor signal segmentsassociated with one or more common values of the therapy parameter orthe measured cardiac parameter such as AVD, pacing rate, heart rate, andcardiac cycle length interval measured at an atrium or ventricle. At860, display 341 presents the phonocardiographic image including thealigned and grouped acoustic sensor signal segments. At 870, the userobserves the phonocardiographic image. In one embodiment the userobserves from phonocardiographic image indications of at least one ofevents and time intervals such as mitral valve closure, aortic valveopening and closure, electromechanical activation delays, isovolumiccontraction time, ejection period, and diastolic filling period.

In one embodiment, display 341 presents the phonocardiographic image andother information according to the user instruction received at 814. Inone embodiment, display 341 displays a planar acoustic sensorsignal-verses-time curve that is the presentation of a selected acousticsensor signal segment presented in a different form. In one embodiment,display 341 enlarges a selected portion of the phonocardiographic image.In one embodiment, display 341 presents an electronic caliper movable bythe user to measure a time interval between any two points along any ofthe acoustic sensor signal segments. In one embodiment, the user adjuststhe brightness, contrast, and/or the color or gray scale mapping relatedto presenting the phonocardiographic image at 814. In one embodiment,receiving the user input at 814 including receiving portions of the userinput along steps 810-870. In one embodiment, receiving the user inputat 814, presenting the phonocardiographic image at 860, and observingthe phonocardiographic image at 870 constitute an iterative process toresult in a presentation that is satisfactory to the user.

Based on observing the phonocardiographic image at 870, the user maydiagnose a cardiac condition at 880 and/or determine a cardiac therapyat 882. Details of steps 880 and 882 are discussed with reference toFIG. 9 and FIG. 10, respectively.

In one embodiment, the method illustrated in FIG. 8 is performed withprogrammer 140. In an alternative embodiment, the method illustrated inFIG. 8 is performed with a computer including components performing thefunctions of signal processor 350, display 341, and user input 342. Inthis alternative embodiment, the acoustic sensor signal and the cardiacsignal are received at 810 and 812, respectively, from a storage mediumon which the signals have been recorded with system 100.

FIG. 9 is a flow chart illustrating one embodiment of a method forphonocardiographic image-based diagnosis. One of the applications of thephonocardiographic image such as phonocardiographic image 780 is toprovide a tool for diagnosis of cardiac conditions based on the acousticsensor signal and the cardiac signal recorded from the patient, with orwithout delivering a cardiac therapy while recording the signals. In oneembodiment, the phonocardiographic image-based diagnosis is performed ona patient suspected to have an abnormal cardiac condition. In anotherembodiment, the phonocardiographic image-based diagnosis is performed toa patient being a therapy candidate to determine whether a particulartherapy is likely to improve the patient's cardiac conditions andhemodynamic performance. In yet another embodiment, thephonocardiographic image-based diagnosis is performed as a follow-upexamination for a patient having been treated with a therapy. In oneembodiment, the phonocardiographic image-based diagnosis provides anon-invasive way to examine a patient, with the cardiac signal and theacoustic sensor signal acquired through surface ECG electrodes and anexternal acoustic sensor. In another embodiment, the phonocardiographicimage-based diagnosis provides a non-invasive way to examine a patientcarrying an implanted device, with the cardiac signal and the acousticsensor signal acquired by the implanted device and telemetered to anexternal device. In yet another embodiment, the phonocardiographicimage-based diagnosis provides a non-invasive way to examine a patientcarrying an implanted device, with the cardiac signal acquired by theimplanted device and telemetered to an external device, and the acousticsensor signal acquired by the external device through an acoustic sensorattached onto the patient.

The method for acquiring, presenting, and using the phonocardiographicimage as discussed above with reference to FIG. 8 is incorporated intothe method for the phonocardiographic image-based diagnosis. At 900, theuser selects a type of cardiac events based on which the acoustic sensorsignal is to be segmented and the acoustic sensor signal segments are tobe aligned. In one embodiment, the user selects the type of cardiacevents. In another embodiment, the user selects a type of diagnosis or aparticular heart sound or a particular time interval to be observed, andsignal processor 350 selects the cardiac event based on the user'sselection. At 905, the user selects an order for arranging the acousticsensor signal segments for presentation. In one embodiment, the userselects a timing interval and/or therapy parameter associated with eachacoustic sensor signal segment. This timing interval and/or therapyparameter then determines the location of each acoustic sensor signalsegment in the stack of the acoustic sensor signal segments of thephonocardiographic image. In another embodiment, the user selects a typeof diagnosis or a particular heart sound or a particular time intervalto be observed, and signal processor 350 sorts, groups, and arranges theacoustic sensor signal segments according to a predetermined defaultarrangement. In one embodiment, the selections made by the user at 900and 905 are received by user input module 342 at 814.

For phonocardiographic image-based diagnostic purpose, observing thephonocardiographic image at 870 includes identifying at least one typeof heart sounds at 972. This includes identifying a type such as thefirst, second, third, and fourth heart sound, or a component of one ofthese heart sounds. In one embodiment, observing the phonocardiographicimage at 870 includes identifying one type of heart sounds based on theacoustic sensor signal amplitude and empirical knowledge temporalrelation between the type of heart sounds and a type of cardiac events.In one embodiment, the user identifies the heart sound by observing theacoustic sensor signal amplitude represented by gray scales or colors.In a further embodiment, the user may adjust the amplitude-gray scale oramplitude-color mapping to change the contrast of the phonocardiographicimage to facilitate the heart sound identification. In one embodiment,observing the phonocardiographic image at 870 further includes observingor detecting a timing trend of the identified type of heart sounds at974. In one embodiment, the user observes the trend of an intervalbetween a type of cardiac events and the identified type of heartsounds. In one specific embodiment, as illustrated in FIG. 7, the userobserves the trend of the interval between atrial event Asense and heartsound S1 over the interval between Asense and V (i.e., AVD or AVI). Thistrend indicates the trend of the electro-mechanical interval between theatrial depolarization and the mitral valve closure over theatrio-ventricular activation interval. In another embodiment, heartsound detector 555 detects a type of heart sounds and presents a timingtrend related to the detected heart sounds on display 341. In a furtherembodiment, the user observes the presented trend to confirm itsaccuracy.

For phonocardiographic image-based diagnostic purpose, diagnosingcardiac condition at 880 includes, in one embodiment, diagnosing acardiac condition at 982 based on whether that type of heart sounds hasbeen identified from the phonocardiographic image at 972. The presenceor absence of certain heart sounds or heart sound components indicateexistence of a cardiac condition. In one embodiment, the user makes adiagnosis of heart failure based on the existence of the third heartsound, S3. In one specific embodiment, as illustrated in FIG. 7, heartsound S3 is present during the non-paced cardiac cycles (associated withthe AVI) but diminishes during most of the paced cardiac cycles(Associated with the AVDs). This indicates that the patient has heartfailure treatable by cardiac pacing. In another embodiment, diagnosingcardiac condition at 880 includes diagnosing a cardiac condition at 984based on the timing trend of the identified heart sound observed ordetected at 974. An abnormal timing trend indicates a deterioratedmyocardium and/or an abnormal electrical conduction system that areassociated with poor hemodynamic performance. In one embodiment, theuser examines the efficacy of a cardiac therapy in treating heartfailure based on a trend of the interval between the atrialdepolarization and the first heart sound. In one specific embodiment, asillustrated in FIG. 7, the Asense-S1 interval is shortened during thepaced cardiac cycles associated with AVD1, AVD2, and AVD3, indicatingthat pacing at these AVDs is effective in shortening the intervalbetween the atrial depolarization and the first heart sound, which isindicative of the electro-mechanical interval between atrialdepolarization and mitral valve closure.

FIG. 10 is a flow chart illustrating one embodiment of a method forphonocardiographic image-based therapy evaluation. One of theapplications of the phonocardiographic image such as phonocardiographicimage 780 is to provide means for determining a suitable therapytreating a cardiac condition. In one embodiment, the phonocardiographicimage provides for an overall visual presentation of results of atherapy evaluation. In one embodiment, as illustrated in FIG. 10, thetherapy evaluation provides for indications of whether a therapy iseffective and an approximately optimal therapy parameter.

The method for acquiring and presenting the phonocardiographic image,including steps 800-880 discussed above with reference to FIG. 8, isincorporated into the method for the phonocardiographic image-basedtherapy evaluation. In one embodiment, programmer 140, and specificallytherapy controller 360 discussed above with reference to FIG. 6,performs steps 1000-1030 on an automatic basis. At 1000, cardiacparameter input 662 receives at least one cardiac parameter related to apatient. In one embodiment, the user enters the cardiac parameter. Inanother embodiment, signal processor 350 measures the cardiac parameterfrom the cardiac signals and/or event markers telemetered from implanteddevice 110. At 1010, therapy parameter calculator 663 calculates aseries of therapy parameters or parameter sets based on the cardiacparameter. At 1020, a therapy protocol including descriptions of asequence of therapies is generated. The therapies each include aparameter set defining the therapy using one of the calculated therapyparameter or parameter set. At 1030, therapy parameter sequencing module669 executes the therapy protocol by sending the therapy descriptions toimplanted device 110 via telemetry link 170, one portion (description ofone of the sequence of therapies) at a time, as timed by timer 668. Thecalculated therapy parameters or parameter sets are each tested duringthe protocol execution.

In an alternative embodiment, the user manually performs steps 1000-1030or portions thereof. At 1000, the user measures or otherwise obtains atleast one cardiac parameter related to a patient. At 1010, the usercalculates therapy parameters or parameter sets based on the cardiacparameter. At 1020, the user generates a therapy protocol containingtherapy descriptions of a sequence of therapies each including one ofthe calculated therapy parameters or parameter sets. At 1030, the usersends the therapy descriptions to implanted device 110 by manuallyentering commands into user input module 342 of programmer 140, oneportion (description of one of the sequence of therapies) at a time,with intervals between sending the portions of the therapy descriptionstimed by the user. In one embodiment, the user enters changes of therapyparameters or parameter sets and causes programmer 140 to send thechanged therapy parameters or parameter sets to implanted device 110such that each therapy parameter or parameter set calculated at 1010 aretested.

The phonocardiograph session discussed with reference to FIG. 8 startsany time after the therapy protocol execution (1030) begins. In oneembodiment, the phonocardiograph session starts at approximately thesame time when therapy protocol execution (1030) begins. In anotherembodiment, the phonocardiograph session starts after the therapyprotocol execution (1030) ends. In a further embodiment, thephonocardiograph session is performed, by using programmer 140, afterthe completion of the therapy protocol execution (1030). In analternative embodiment, the phonocardiograph session is performed, byusing a computer in which signal processor 350 is installed, after thecompletion of the therapy protocol execution (1030).

For purposes of the phonocardiographic image-based therapy evaluation,observing the phonocardiographic image at 870 includes identifying heartsounds possibly affected by the therapy at 1072. In one embodiment, thisincludes identifying a particular type of heart sounds as predeterminedby a purpose for the therapy evaluation. In one embodiment, observingthe phonocardiographic image at 870 further includes observing ordetecting a timing trend of the identified heart sounds at 1074. In oneembodiment, the user observes the trend of an interval between a type ofcardiac events and the identified type of heart sounds. In anotherembodiment, heart sound detector 555 detects a type of heart sounds andpresents a timing trend related to the detected heart sounds on display341. In a further embodiment, the user observes the presented trend toconfirm its accuracy.

For purposes of the phonocardiographic image-based therapy evaluation,determining a cardiac therapy at 882 includes determining the cardiactherapy based on an outcome of observing the phonocardiographic image at870. In one embodiment, determining the cardiac therapy at 882 includesdetermining, at 1082, an efficacy of each of the evaluated therapies,based on whether the therapy is observed to affect a presence of thetype of heart sounds to be identified at 1072 and/or the trend of thetype of heart sounds observed or detected at 1074. In a furtherembodiment, if it is determined at 1082 that the therapy is to bedelivered, determining the cardiac therapy at 882 includes determining atherapy parameter of parameter set at 1084, based on the effect of thetested therapy parameters or parameter sets on the presence of the typeof heart sounds to be identified at 1072 and/or the trend of the type ofheart sounds observed or detected at 1074. In one embodiment, thisincludes selecting one of the tested therapy parameters or parametersets. In another embodiment, this includes determining a therapyparameter or parameter set based on the presence of the type of heartsounds to be identified at 1072 and/or the trend of the type of heartsounds observed or detected at 1074.

At 1090, if it is determined at 1082 that the therapy is to bedelivered, the therapy is delivered to the patient, with the oneparameter or parameter set determined at 1084. In one embodiment, thisincludes programming the parameters or parameter sets to implantabledevice 110 using programmer 140. The parameter or parameter set is thenstored in the memory circuit of implant controller 323. In one furtherembodiment, the method of phonocardiographic image-based therapyevaluation is repeated on a predetermined schedule. In another furtherembodiment, the method for phocardiographic image-based therapyevaluation is repeated on a needy basis, as determined by the user. Ifthe repeated phonocardiographic image-based therapy evaluation resultsin a new parameter or parameter set, this new parameter or parameter setis programmed into implanted device 110 to replace the parameter orparameter set stored in the memory circuit of implant controller 323.

FIG. 11 is a flow chart illustrating one embodiment of a method forphonocardiographic image-based AVD optimization. This embodimentprovides for an example of the method for phonocardiographic image-basedtherapy evaluation discussed above with reference to FIG. 10. Otherapplications includes, by way of example, but not by way of limitation,determination or optimization of pacing site or sites, pacing mode, andother pacing interval or delay parameters.

In the embodiment illustrated in FIG. 11, the phonocardiographic imagesuch as phonocardiographic image 780 provides for means for determiningan approximately optimal AVD based on a pacing therapy evaluation. Theapproximately optimal AVD is an AVD associated with an approximatelyoptimal hemodynamic performance as indicated by one or more heartsounds. The phonocardiographic image provides for a visual presentationof results associated with all AVDs tested during one therapy (pacing)protocol execution.

The method for acquiring and presenting the phonocardiographic image,including steps 800-880 discussed above with reference to FIG. 8, isincorporated into the method for the phonocardiographic image-based AVDoptimization. In one embodiment, programmer 140, and specificallytherapy controller 360 discussed above with reference to FIG. 6,performs steps 1100-1130 on an automatic basis. At 1100, cardiacparameter input 662 receives an intrinsic AVI measured from the patient.In one embodiment, the user enters the AVI, which is previouslymeasured, through user input module 342. In another embodiment, signalprocessor 350 measures the AVI from event markers telemetered fromimplanted device 110. At 1110, therapy parameter calculator 663calculates values of a predetermined number of AVDs based on the AVI. Inone embodiment, the number of AVDs to be evaluated depends on acompromise between time required for the pacing therapy evaluation and adegree of accuracy in identifying an optimal AVD. In one embodimentcorresponding to the illustration of FIG. 7, five AVDs, AVD1-AVD5, arecalculated based on the AVI. In one specific embodiment, AVD1-AVD5 areevenly spaced, with AVD1 near zero and AVD5 near the AVI. In anotherspecific embodiment, AVD1-AVD5 are evenly spaced, AVD1 is about 25 ms,and AVD5 is about 30 ms shorter than the AVI. At 1120, a pacing protocolincluding descriptions of a sequence of pacing therapies is generated.In one embodiment, the pacing therapies include VDD mode pacingtherapies each including one of the calculated AVDs. In one embodiment,the pacing therapies include DDD mode pacing therapies each includingone of the calculated AVDs. At 1130, therapy parameter sequencing module669 executes the pacing protocol by sending the therapy descriptions toimplanted device 110 via telemetry link 170, one portion (description ofone of the therapies) at a time, as timed by timer 668. The calculatedAVDs are each tested during the protocol execution.

The phonocardiograph session discussed with reference to FIG. 8 startsany time after the pacing protocol execution (at 1130) begins. In oneembodiment, the phonocardiograph session starts at approximately thesame time when pacing protocol execution (at 1130) begins. In anotherembodiment, the phonocardiograph session starts after the therapyprotocol execution (at 1130) ends. In a further embodiment, thephonocardiograph session is performed after the completion of thetherapy protocol execution (at 1130) by using programmer 140. In analternative embodiment, the phonocardiograph session is performed afterthe completion of the therapy protocol execution (1130) by using acomputer in which signal processor 350 is installed.

For purposes of the phonocardiographic image-based AVD optimization,observing the phonocardiographic image at 870 includes observing a trendof a heart sound over the tested AVDs and the AVI at 1176. In onespecific embodiment, referring to FIG. 7, this includes observing atrend of the interval (A-S1 interval, or T_(A-S1)) between atrial eventAsense and heart sound S1 over the AVI and AVD1-AVD5. The A-S1 intervaltrend indicates the trend of the electromechanical interval between theatrial contraction and the mitral valve closure over non-pacing (at AVI)and pacing at AVD1-AVD5. In one embodiment, the A-S1 interval isreferred to as P-S1 interval because Asense marks represent detectedP-waves indicative of intrinsic atrial depolarization. In anotherembodiment, the A-S1 interval also includes the interval betweendelivery of an atrial pacing pulse (Apace) and heart sound S1.

For purposes of the phonocardiographic image-based AVD optimization,determining a pacing therapy at 882 includes determining theapproximately optimal AVD based on an outcome of observing thephonocardiographic image at 870. In one embodiment, determining thepacing therapy at 882 includes determining whether the pacing therapyevaluation shows that at least one of the AVDs is associated with asignificant improvement the patient's hemodynamic performance asindicated by a heart sound trend. In a further embodiment, if it isdetermined at 1186 that at least one of the AVDs is associated with asignificant improvement the patient's hemodynamic performance,determining the cardiac therapy at 882 includes determining theapproximately optimal AVD at 1188. In one embodiment, this includesdetermining the approximately optimal AVD based on the A-S1 intervaltrend over the tested AVDs. In another embodiment, this includesdetermining the approximately optimal AVD by selecting one of the testedAVDs based on the A-S1 interval trend over the tested AVDs. In oneembodiment, as discussed below with reference to FIG. 12 and FIG. 13,determining the pacing therapy at 882 includes determining anapproximately optimal AVD for maximizing ventricular contractility byusing the phonocardiographic image.

At 1190, if it is determined at 1186 that the pacing therapy iseffective, the pacing therapy is delivered to the patient, with theapproximately optimal AVD determined at 1188. In one embodiment, thisincludes programming the approximately optimal AVD into implanted device110 using programmer 140. In one embodiment, the approximately optimalAVD is programmed into implanted device 110, and is then stored in thememory circuit of implant controller 323. In one further embodiment, themethod of phonocardiographic image-based AVD optimization is repeated ona predetermined schedule. In another further embodiment, the method ofphonocardiographic image-based AVD optimization is repeated on a needybasis, as determined by the user. If the repeated phonocardiographicimage-based AVD optimization results in a new approximately optimal AVD,this new approximately optimal AVD is programmed into implanted device110 to replace the AVD stored in the memory circuit of implantcontroller 323.

FIG. 12 is an illustration of one embodiment of a method for AVDoptimization for maximum ventricular contractility. One strategyoptimizing hemodynamic performance with CRT is to maximize ventricularcontractility. One measure of ventricular contractility is the maximumrate of ventricular pressure increase, dP/dt_(max), during isovolumiccontraction. Direct measurement of dP/dt requires intraventricularcatheterization with a pressure transducer. On the other hand, it hasbeen observed that the timing of certain heart sounds correlates to thestrength of heart contraction. Thus, heart sound timing is capable ofbeing a surrogate measure of relative dP/dt changes that does notrequire an intraventricular pressure sensor. It is believed thatventricular contractility is maximized when the onset of S1 due topacing coincides with the intrinsic S1 to achieve the best fusion ofpaced and intrinsic activations.

FIG. 12 illustrates an acoustic sensor signal segment 1292A and anotheracoustic sensor signal segment 1292B each indicative of S1. Cardiacevents A (sensed or paced atrial events) and V (sensed or pacedventricular events) are marked on both acoustic sensor signal segments.Acoustic sensor signal segment 1292A is associated with ventricularpacing at a relatively short AVD, AVD_(S), and including S1 _(S) due tothe pacing at AVD_(S). The A-S1 interval, T_(A-S1, S), indicates the S1timing associated with pacing. Acoustic sensor signal segment 1292B isassociated with an intrinsic ventricular contraction or ventricularpacing at a relatively long AVD, AVD_(L), and including S1 _(L), whichis the intrinsic S1. The A-S1 interval, T_(A-S1, L), indicates theintrinsic S1 timing not affected by pacing. To achieve an approximatelymaximum ventricular contractility, a ventricular pacing pulse isdelivered to cause approximately simultaneous paced and intrinsicactivations. The approximately optimal AVD is an AVD at with theventricular pacing minimally shortens the intrinsic A-S1 interval.

FIG. 13 is a flow chart illustrating one embodiment of a method forphonocardiographic image-based AVD optimization for maximum ventricularcontractility. At 1300, an acoustic sensor signal indicative of S1 isrecorded. A cardiac signal indicative of cardiac events A (sensed orpaced atrial events) and V (sensed or paced ventricular events) is alsorecorded. Ventricular pacing pulses at a plurality of AVDs are deliveredwhile the acoustic sensor signal and cardiac signal are recorded at1310. In one embodiment, the pacing pulses are delivered by executing apacing protocol that is discussed above with reference to FIG. 11. At1320, an S1 timing trend is determined as a curve indicating thebeginning of S1 relative to cardiac event A. In one embodiment, theacoustic sensor signal is presented as the phonocardiographic image,which includes acoustic sensor signal segments aligned by cardiac eventA, and the S1 timing trend is observed from the phonocardiographicimage. At 1330, a turning point (“knee”) is detected from the S1 timingtrend. The knee represents a point at which the A-S1 interval begins toshorten as a result of pacing. In one embodiment, the S1 timing trend isa curve indicating the beginning of heart sound S1 on the stackedacoustic sensor signal segments of the phonocardiographic image. In oneembodiment, heart sound detector 555 detects the leading edge of thefirst heart sounds and presents it on display 341. In a furtherembodiment, the user observes the detected leading edge of the firstheart sounds to confirm its accuracy before locating the turning point.At 1340, an approximately optimal AVD is determined as the longest AVD,among the tested plurality of AVDs, at the knee. In other words, theapproximately optimal AVD is the longest AVD associated with a visiblyshortened A-S1 interval.

FIG. 14 is a flow chart illustrating one embodiment of another methodfor phonocardiographic image-based AVD optimization for maximumventricular contractility. At 1400, an acoustic sensor signal indicativeof S1 sounds is recorded. A cardiac signal indicative of atrial andventricular electrical events is also recorded. Ventricular pacingpulses are delivered while the acoustic sensor signal and cardiac signalare recorded at 1410. The acoustic sensor signal includes indications ofS1 associated with paced ventricular activation and S1 associated withintrinsic ventricular activation. S1 associated with the pacedventricular activations are observed at AVDs that are sufficient shortsuch that the ventricular pacing visibly shortens the A-S1 interval. S1associated with the intrinsic ventricular activations are observed whenventricular pacing is not delivered or at AVDs that are sufficientlylong such that the ventricular pacing does not visibly shortens the A-S1interval. In one embodiment, the pacing pulses are delivered byexecuting a pacing protocol that is discussed above with reference toFIG. 11. At 1420, an S1 associated with a paced ventricular activation,S1 _(S), is detected. At 1430, a short A-S1 interval, T_(A-S1, S), ismeasured between a cardiac event A and S1 _(S), where S1 _(S) isadjacently subsequent to cardiac event A. At 1440, an S1 associated withan intrinsic ventricular activation, S1 _(L), is detected. At 1450, along A-S1 interval, T_(A-S1, L), is measured between a cardiac event Aand S1 _(L), where S1 _(L) is adjacently subsequent to cardiac event A.In one embodiment, steps 1420-1450 are performed based on a display ofacoustic sensor signal such as the phonocardiographic image. In onespecific embodiment, S1 _(S) is one of the S1 sounds observed to beassociated with the shortest A-S1 interval, typically seen with theshortest AVD, and S1 _(L) is one of the S1 sounds observed to beassociated with the longest A-S1 interval, typically seen with AVI(non-paced cardiac cycles) as well as the longest AVD. In oneembodiment, the user measures the A-S1 intervals on thephonocardiographic image with the electronic caliper of user inputmodule 342. In another embodiment, signal processor 350 measures theA-S1 intervals automatically. In one embodiment, each A-S1 interval ismeasured between the cardiac event A and the beginning of heart soundS1. In one specific embodiment, cardiac event A is represented by anatrial event marker. At 1460, the approximately optimal AVD isdetermined by using a formula:AVD_(OPT)=AVD_(S) +T _(A-S1,L) −T _(A-S1,S),where the AVD_(OPT) is the approximately optimal AVD, and the AVD_(S) isthe AVD associated with the detected S1 _(S).

In a specific embodiment combining methods illustrated in FIG. 7(phonocardiographic image 780), FIG. 11 (pacing protocol withAVD1-AVD5), FIG. 13, and FIG. 14, S1 _(S) is detected at AVD1, and S1_(L) is detected at AVD5. The user measures A-S1 intervals associatedwith AVD1 and AVD5. The approximately optimal AVD is determined as:AVD_(OPT)=AVD1+T _(A-S1,AVD5) −T _(A-S1,AVD1),where the T_(A-S1,AVD5) is the T_(A-S1) corresponding to AVD5 (thelongest AVD), and the T_(A-S1,AVD1) is the T_(A-S1) corresponding toAVD1 (the shortest AVD).

In a further embodiment, a first estimate of the approximately optimalAVD is determined based on results of executing a first pacing protocolincluding a predetermined number of “coarsely spaced” AVDs. The methodof AVD optimization is repeated, with another predetermined number of“finely spaced” AVDs having values near the first estimate used togenerate a second protocol. The approximately optimal AVD is thendetermined based on the results of executing the second pacing protocol.Both the first estimate and the final approximately optimal AVD isdetermined by the “knee” detection method discussed with reference toFIG. 13, the AVD_(OPT) formula discussed with reference to FIG. 14, or acombination of both. More than one repetition can be performed asnecessary or desired. This embodiment requires more time but likelyresults in an approximately optimal AVD that is closer to the AVDassociated with the optimal hemodynamic performance. In a specificembodiment, the first estimate of the approximately optimal AVD isdetermined by using the AVD_(OPT) formula above, after generating andexecuting the first pacing protocol including the predetermined numberof “coarsely spaced” AVDs. The approximately optimal AVD is thendetermined by locating a knee in the leading edge of the first heartsounds (S1 timing trend) in the phonocardiographic image resulted fromexecuting the second pacing protocol. The knee corresponds to theapproximately optimal AVD, which is the longest AVD (among the finelyspaced AVDs) associated with a visibly shortened A-S1 interval(T_(A-S1)).

It is to be understood that the above detailed description is intendedto be illustrative, and not restrictive. For example, thephonocardiographic image can be formed with a cardiac signal and anacoustic sensor signal acquired by any implanted or external medicaldevice providing for ECG and heart sound monitoring. Many otherembodiments will be apparent to those of skill in the art upon reviewingthe above description. The scope of the invention should, therefore, bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

1. A system, comprising: an acoustic sensor signal input to receive anacoustic sensor signal indicative of heart sounds; a cardiac signalinput to receive a cardiac signal indicative of cardiac events; a signalsegmenting module coupled to the acoustic signal input and the cardiacsignal marker input, the signal segmenting module configured topartition the acoustic sensor signal into acoustic sensor signalsegments; a signal alignment module coupled to the signal segmentingmodule, the signal alignment module configured to temporally align theacoustic sensor signal segments by first type events selected from thecardiac events and the heart sounds; a display coupled to the signalalignment module, the display configured to present a phonocardiographicimage including the aligned acoustic sensor signal segments; a signalgrouping module coupled to the signal alignment module, the signalgrouping module configured to sort and group the acoustic sensor signalsegments according to a grouping instruction.
 2. The system of claim 1,wherein the signal grouping module is configured to sort and group theacoustic sensor signal segments according to a cardiac pacing parameter.3. The system of claim 2, wherein the signal grouping module isconfigured to sort and group the acoustic sensor signal segmentsaccording to an atrio-ventricular delay.
 4. The system of claim 3,wherein the signal segmenting module is configured to partition theacoustic sensor signals into segments each including at least onecomplete cardiac cycle.
 5. The system of claim 1, comprising a userinput coupled to the display, the user input configured to receive usercommands and map intensity of the acoustic sensor signal to a spectrumof colors according to the user commands.
 6. The system of claim 1,comprising a user input coupled to the display, the user inputconfigured to receive user commands and map intensity of the acousticsensor signal to gray scales according to the user commands.
 7. Thesystem of claim 1, comprising a heart sound detector coupled to thesignal grouping module, the heart sound detector configured to detectselected type heart sounds and presents representations of the detectedheart sounds in the phonocardiographic image.
 8. The system of claim 1,wherein the acoustic sensor comprises an accelerometer.
 9. The system ofclaim 1, wherein the acoustic sensor comprises a microphone.
 10. Asystem, comprising: means for partitioning an acoustic sensor signalinto acoustic sensor signal segments, the acoustic sensor signalindicative of heart sounds; means for aligning the acoustic sensorsignal segments by first type events selected from cardiac events andthe heart sounds; means for presenting a phonocardiographic imageincluding the aligned acoustic sensor signal segments; means forgrouping the aligned acoustic sensor signal segments according to agrouping instruction.
 11. The system of claim 10, comprising means forsensing the acoustic sensor signal.
 12. The system of claim 11,comprising means for sensing a cardiac signal indicative of the cardiacevents.
 13. A method, comprising: receiving an acoustic sensor signalindicative of heart sounds; receiving a cardiac signal indicative ofcardiac events; associating the acoustic sensor signal and the cardiacsignal using a common timing reference; partitioning the acoustic sensorsignal into acoustic sensor signal segments; aligning the acousticsensor signal segments by first type events selected from the cardiacevents and the heart sounds; sorting and grouping the acoustic sensorsignal segments according to a grouping instruction; and converting theacoustic sensor signal segments into image pixels for presentation. 14.The method of claim 13, wherein partitioning the acoustic sensor signalcomprises partitioning the acoustic sensor signal according to a userinstruction.
 15. The method of claim 13, comprising sorting and groupingthe acoustic sensor signal segments according to a user instructionreceived by a medical device programmer.
 16. The method of claim 15,wherein grouping the aligned acoustic sensor signal segments comprisesarranging the aligned acoustic sensor signal segments using a cardiactiming interval.
 17. The method of claim 15, wherein arranging thealigned acoustic sensor signal segments comprises arranging the alignedacoustic sensor signal segments using a cardiac pacing parameter. 18.The method of claim 17, wherein arranging the aligned acoustic sensorsignal segments comprises arranging the aligned acoustic sensor signalsegments using an atrioventricular pacing delay.
 19. The method of claim18, wherein aligning the acoustic sensor signal segments comprisesaligning the acoustic sensor signal segments by an atrial event beingone of a sensed intrinsic atrial depolarization and a delivery of atrialpacing pulse.
 20. The method of claim 13, wherein receiving the acousticsensor signal comprises receiving the acoustic sensor signal from animplanted acoustic sensor.